Two-stage drill for mechanical decoking or the like



Oct. 25, 1966 J. M. FoRsYTH 3,280,415

TWO-STAGE DRILL FOR MECHANICAL DECOKING OR THE LIKE Filed April 20, 1964 5 Sheets-Sheet l /Z l i 25 'l if, 22

Oct. 25, 1966 J. M. FoRsYrH TWO-STAGE DRILL FOR MECHANICAL DECOKING OR THE LIKE 5 Sheets-Sheet 2 Filed April 20, 1964 J. M. FoRsYTH 3,280,416 TWO-STAGE DRILL FOR MECHANICAL DECOKING OR THE LIKE Oct.. 25, 1966 5 Sheets-Sheet 3 Filed April 20, 1964 MJ Q1/WIM ATTORNEYS m mi w,

,w 7.. R. s 5 mm El NF T4. T /JQEV 1 5 M :J /l 03 M ML MM 9 5 I BY Oct. 25, 1966 J. M. FoRsYTH 3,280,416

TWO-STAGE DRILL FOR MECHANICAL DECOKING OR THE LIKE Filed April 20, 1964 5 Sheets-Sheet 4 037557 /W isa si M- lm l@ im \i f4 BY l y ATTORNEYS Oct. 25, 1966 J. M. FoRsYTH 3,280,416

TWO-STAGE DRILL FOR MECHANICAL DECOKING OR THE LIKE F'iled April 20. 1964 5 Sheets-Sheet 5 ATTORNEYS United States Patent O 3,280,416 TWO-STAGE DRILL FOR MECHANICAL DECOKING R THE LIKE James M. Forsyth, RO. Box 18602, Houston, Tex. Filed Apr. 20, 1964, Ser. No. 361,122 21 Claims. (Cl. 15-104.1)

My invention relates to a drill-bit construction particularly adapted to the generation of large-diameter bores, as in application to the periodic removal of accumulated solid matter within a chamber or reactor vessel forming part of a large industrial processing operation, such as ore processing, petroleum refining, vand the like.

In industrial processing of the general character indicated, large chambers, such as Vertical cylindrical towers, are employed to accumulate solidified reaction products. For example, in petroleum refining, hard coke is collected in a coking tower of the order of l0() feet or more in height and more than feet in diameter. When the tower is nearly filled, it is cleaned in a boring operation which proceeds from the bottom up, via an -access port of limited diameter at the center of the bottom. The fragmented coke drops through the port as drilling proceeds. Conventionally, a series of successive drilling operations is performed, in order to progressively enlarge the cleared volume within the tower, and with each successive drilling operation a new drill bit, of :awkward massive proportions, must be maneuvered into position on the drilling apparatus, in place of the bit previously used. The mounting, dismounting and other manipulations involved in this procedure not only require the supply and employment of different bits but also great and costly down-time. When coking towers are employed in multiple, so that one tower may be cleared while yanother is serving the refining operation, the complexity of drill or de-coking operations is compounded.

It is, therefore, an object of the invention to provide an improved drill-bit construction of the character indicated.

Another object is to provide a drill-bit which will be universally applicable for various bore diameters so that the need for changing drill bits may be substantially reduced.

A further object is to provide a drill-bit meeting the above objectives and employable at a rst or pilot diameter on a first cut inwardly into the material to be bored, and employable at an enlarged diameter on a second cut immediately following the first cut and as the bit is being withdrawn from the material.

Still another object is to provide efficient stabilization for a drill bit of the character indicated, regardless of the diameter of cut.

It is a general object to meet the above objects with a drill-bit which, for all its necessary bulk, is essentially` simple, efiicient, non-fouling, self-clearing, and readily adaptable to existing reactors or towers and their associated drilling mechanisms.

Other objects and various further features of novelty and invention will be pointed out or will occur to those skilled in the art from a reading of the following specification in conjunction with the accompanying drawings. In said drawings7 which show, for illustrative purposes only, a preferred form of the invention:

FIG. l is a simplified overall view in elevation of a multiple-tower or reactor installation with its associated c ICC drilling equipment, all served by the single drill bit of the invention, one of the towers and its drilling mechanism being partly broken away and shown in section to disa play my drill-bit in use;

FIGS. 2, 3 and 4 yare views similar to FIG. 1, but show different relations between the drill-bit and a reactor or tower during various parts of the cycle of employment of the drill-bit to completely clean the tower;

FIG. 5 is an enlarged view in elevation of my drillbit, with part of the associated drilling equipment, pr1- marily broken-away :and in vertical section;

FIGS. 5a 'and 5b are sectional views in the planes Sa-Sa and Sb-Sb, respectively, of FIG. 5;

FIG. 6 is a plan view of my drill-bit, with the eXpansion arms shown in phantom outline and partly in section through pinned locations, the phantom outlines serving to illustrate the drill-diameter extent for each of two operations with my drill-bit;

FIG. 7 is an enlarged fragmentary sectional View taken in the sectioned plane of FIG. 5 and showing seal construction;

FIG. 8 is an enlarged `view in perspective of my drillbit, positioned for pi.lot-boring;

FIG. 9 is a view similar to FIG. 8, with the parts positioned for enlarged diameter boring; and

FIG. 10 is a fragmentary view similar to FIGS. 8 and 9 to illustrate an intermediate position of the parts.

Briefly stated, the invention contemplates an improved drill-bit for the purposes indicated and featuring two stages of operation, the first stage being one in which the effective bore diameter of the drill-bit determines a first and reduced pilot bore. The pilot bore is developed on a first and inwardly `directed pass of the drill into the material being bored. The second stage or phase of operation of the drill bit becomes effective, upon completion of this first pass, (1) to expand the effective cutting diameter by as much as a factor of two or more, and (2) to accomplish this second stage of the drillbit operation during the withdrawal of the bit from the material being bored; thus, as the bit is being withdrawn, the enlarged bore is developed. Means will be described in association with such a drill bit for reliably stabilizing the alignment of the bit as it progresses through its first and its second stages of cutting; other features making for simplicity,

ruggedness and reliability of operation, will also be described.

Referring to FIG. 1 of the drawing, the invention is shown in application to a multiple tower or multiple reactor installation, as may be employed in petroleum refining for the accumulation of solid matter such as coke. In FIG. l, two such towers 10-11 are shown. Each of the towers may extend for its effective capacity for an overall vertical length in the order of feet and may have an internal diameter of the order of 20 or 30 feet. Each tower is spaced above ground height on supporting legs, suggested at 12, and providing unobstructed access to a central closure at the lower end of an inwardly tapering conical funnel portion 13 at the bottom of the tower. Normally, .a door or closure 14 defines the bottom of one of the towers 10-11 while it is accumulating solid matter as part of the refining or other process with which the tower may be involved. The detail of said door is not important to my invention, but it will be understood to be suitably secured as by means of plural angularly spaced bolts 15, such that when desired the bolts may be removed or loosened to define yal1-opening of approximately one-half the internal diameter of the tower 10 or 11. For. the situation depicted in FIG. l, the tower 11 is being used in conjunction with a normal industrial process, involving accumulation of coke. The tower at 10, however, having accumulated its full charge of coke must now be cleaned, and it is therefore shown in greater detail in the course of a cleaning operation of the drill-bit of the invention.

Conventionally, each of the towers 10-11 is served by its own drilling equipment comprising an elongated casing or well at 16 for the tower 10, and at 17 for the tower 11. The casings 16-17 extend in axial lalignment with the towers which they serve and are buried beneath grade level, designated 18. The casings 16,-17 accommodate mechanism popularly known as Kellys, being,y as shown for the casing 16, an elongated splined shaft 19 journal-led at the base end ina suitable bearing 20 slidable for the major length of the casing 16. The upper end of the kelly shaft 19 supports the drill-bit 21 which in the form shown incorporates the invention. Rotary drive for the kelly 19 is imparted via a suitable driveY gear (not shown) carried on a drive car assembly 22. The car 22 will be understood to be movable on rails extending from tower 10 to tower 1-1 so that, when necessary, car 22 can be positioned in driving alignment with the kelly of the particular tower and casing (l-16, or v111-17) with which it is to be connected. The car 22 will be understood to carry motor mechanism 23, appropriate ge-aringand the like to drive the output gear which has splined engagement with the Kelly shaft 19.V The motor 23 in FIG. l will thus be understood to provide basic rotary drill drive via the kelly 19 to the drill-bit 21.

Basic to the operation of the drill mechanism shown in FIG. 1 isv the elevation of the drill head or bit 21 as the drilling operation proceeds, This is accomplished hydraulically, as by means of water pressure supplied at the port 24 to establish a driving pressure head in the casing or cylinder 16 beneath the piston 20; since this mechanism forms no part of the invention,y it is not shown in.V

tion to the base of tower 11, and up anrinclineA determined by an'upstanding loading structure 28, for ultim-ate discharge by chute 20 to a railroad car 30 or other means of carting away theV collected material disgorged by boring.

Referring to FIGS. to 10, the drill-bit of my invention is seen to comprise separate pilot-bore cutting means and what I have termed auxiliary-bore cutting means. The` pilot-bore cutting means is relatively fixed to a head structure 31 which is in essence a tubular casing with a closed upper end which, for non-fouling purposes, may be tapered and conical asY shownV at 32. The pilot boring elements are shown as arms 33-34-35 spaced equally angularly with respect to each other and about the drill axis. Each of these arms presents cutting means in the form of spaced teeth such as the teeth 36-3636"36" at the forward or pilot-bore cuttingedge Of the arm 33. Corresponding teeth on the arms are similarly designated with increasing primed notation at successively :larger rladii, but with the designation 37 for teethv on arm 34, and with 38-for teeth on arm 3S. Preferably, all of the cutting elementsV of the pilot cutter arms 33-34-35 are disposed to cut inl essentially the` same surface of revolution at theA same time, the teeth being radially spaced and interlaced so that each tool covers a slightly different radius of cut from all the other teeth; thus,I the cutting radii of teeth 36` on arm 33 are interlaced with the cutting radii of the teeth 37 on arm 34, and similarly with radii of the teeth 38 on arm 35. Generally, Vthe alignment of the cutting elements is such as to generate a cone directed in the direction of boring and hence upwardly for the case of the pilot-boring elements. At the center, teeth 39-40-41 associated with the respective cutting arms converge and are connected as by Welding, there being preferably an opening, suggested at 42, so that the drill bit as a whole may be hoisted and manipulated, as will be clear.

Stabilizing shoes are provided at the end of each of the cutting arms 33-34-35 and are shown as of limited arcuate extent and positioned at essentially the pilot-bore radius. The shoe 43 is fastened at the end of arm 33; the shoe 44 forms part of arm 34; Iand the shoe 45 forms part of arm 35. Preferably the axially forward or up- Wardly facing edge of each of the shoes 4.3-44-45 is beveled, as suggested at 43' 'and 44', with a taper which permits the upper edge (as at 45 for the shoe 43) to perform a cleaning .or clearing functionV separating loose or partly dislodged clinkers as. they are dislodged by boring from the solid accumulated mass, the clinkers being allowed to drop free out of the bottom of the tower 10.

As previously indicated, rotary motion is imparted to the drill-bit by Way of the Kelly splined tube or shaft 19. The top of this shaft extends well .into the bore of the drill head 31, and. is shown fastened to a closure member or plug 47. The plug 47 has a radial shoulder which seats upon the upper end of the Kelly tube 19 and which fits removably within the bore and in the otherwise closed bottom 4of an inner tubular member 48 slidably received within the head 31. In the relation shown in FIG. 5, the closed end of the head 31 sits squarely upon both the plug 47- and the upper end of the tubular member 48. Pin means 49, offset from the central axis of the drill, will be understood to passfthrough both the plug 47 and the adjacent part of the inner tubular member 48. Also, an` access port 5t) in the outer tubular member or head 31 provides means for access to the pin 4 9 for insertion and removal of the same. In FIGS. 5a, 8 and 9, this access port in the outer tubular member `or head 31 Ais shown closed by a plug member, having the designation 50'.

In FIG. 5a, a second plug 50 is shown in alignment with the pin 49 andV with the first plug 50 so that, if necessary, the pin may be driven tout by applying a blow a-t one end. In the form show-n, the pin 49 is provided with a threaded end 49 for more accurate and positive retention in a suitably tapped lateral bore in the wall of tubular member 4S.

In order that rotary driving motion may be imparted to .the drill-bit and, in particular, tothe pilot cutting parts 33-34-35 thereof, the inner and 'ou-ter' tubular members 48-31 are shown to have splined engagement With each other at 51, th-us permitting at the same time a certain degree or extent oftelescoping Arelative axial displacement, suggested by the axial clearance between the upper end 52a lof the spline and the uppermost end of the inner t-ubula-r member 48. Thus, upon rotation of the kel-ly 19, the cutting elements are positively driven by way of the p-in 49 and the spline 51.

In -the arrangement shown, the relative axial telescoping movement afforded to the inner and outer tubular members 48-31 is facilitated by provision of spaced sets of roller or anti-friction elements, suggested at 52-53 in FIG. 5. Each of the elements 527-53 is shown received in an elongated radially inwardly directed groove or passage 54 formed in the bore `of the outer tubular member or head 31', and its location is determined by pinned suspensions 52-53 from the side walls of the groove 54. This is perhaps -bet-ter illustrated in FIG. 5b wherein fastening elements 55-56 serve to, retain pivot pin 52' in place. The 4rolling elements 52-53 and their .spaced counterparts, .suggested in phantom at 57-58v in FIG. 5b (being equally angularly spaced locations with respect to the location of elements 52-53) will be understood -to provide accurate, mutual axial .alignment of the telescoping tubular members 48-31, whatever their relative .axial position. Furthermore, these rolling elements (S2-53, etc.) will be understood t-o ride uniformly on the outer surface of the inner tubular element 48.

As indicate-d in FIG. 5, basic stability and more efficient drive for rotation of the drill bit are afforded by additional keyed or splined engagement of the lower or hub part 59 of the inne-r tubular member 48 with the spline of the Kelly shaft 19.

In accordance with the teachings of the invention, the lower or hub par-t 59 of the inner tubular member 48 also forms part of a yoke by mea-ns of which plural bracket members 60-61-62 are rigidly positioned on the inner tubular member 43. Each of the bracket members 60- 61-62 extends radially outwardly and is shown to terminate in a stabilizing shoe (.as at 60'-6-1-62), each stabilizing shoe being preferably axially spaced in relation to the shoes 43-44-45 and essentially equally angularly spaced with respect to each -othe-r. The shoes 60- 61-62 are provided at the same pilot-bore radius and are shown with bevelled upper and lower edges to promote smooth piloting -of the assembly on a generated pilot bore.

Each of the brackets -60-61-62 is shown provided with one extensive flat face, such as the face 63 on bracket 69. This at face extends generally radially and in alignment with the central axis of the drill-bit and is `also essentially parallel with that axis. The face 63 terminates at its inner or root end in an enlarged pocket or recess 64 in the body of 59, so that the at face 63 may extend as far radially inwardly as is tolerable under the circ-umstances. An auxiliary cutting arm 65 is pinned at 66 for pivoted suspension from the bracket 60; arm 65 has an enlarged fa-ce for extensive a-rea of bearing contact with the at face 63 of bracket 60. The location at which arm 65 is pivoted at 66 is short of the radially inner limit of the arm 65 so that the heel of said arm (no-ted at 67) may be projected into and received .and located by the recess 64 when the arm 65 has been operated to the extended position shown in FIG. 5. The particular arrn 65 is shown to have a normal outwardly extended position in which it is canted in a direction reversed from the slope of arms 33434-35 and is provided with lower cutting-edge elements designated 68-6S686S. The outermost too-th e-lement 69 carrie-d by the arm 65 is shown slightly outwardly directed so that it may clear a path which is non-fouling with the outer tip of .arm 65.

Positioning support for the Iarm 65 is shown to be determined by a link 70 pinned at its inner end at 71 to a bracket o-r lug 72 forming part of the outer tubular member or head 31. The outer limit of the link 70 is pinned at 73 to a point on the arm 65 outwardly olset from the pivot 66.

It will be understood that further auxiliary cutting arm 74-75 carrie-d by brackets 61-62 may involve essentially the same suspended relationship as .already described for the case of arm 65, the net result being to provide auxiliary cutting arms 65-74-75 at equally angularly spaced locations that are preferably interlaced with the similar equally -angularly spaced .arms 33-34-35 of the pilotcutting elements. It will be fur-ther understood that, as with the cutting elements or teeth of the respective pilotcutting arms 33-34-35, the teeth 6S-68'-6868 of arm 65 .are so located as to individually genera-te cutting radii that are .interlaced with radii cut by corresponding teeth of the other auxiliary cutting arms 74-7-5.

It will be seen that upon telescoping relative axial displacement of the inner and o-uter tubular members 48-31, the links (as at 70) are caused to simultaneously opera-te arms 65-74-75 back and forth between their retracted and extended positions, the extended relation being shown in solid outlines in FIG. 5 and in FIG. 6.

For purposes of sealing the relatively movable parts against dust and against contact with coke, clinkers and other foreign matter, I show at 76 an axially expandable sea-l structure covering the exposed overlap of tubular members 31-48. The seal structure 76 is shown as a bellows or boot secured at its upper end to the base of the head 31 and secured at its lower end to the enlarged hub 59 of the inner tubular member 43. In FIG. 7, anchoring screws 77-78 secure lthe upper and lower limi-ts of the seal means 76 by way of clamp rings 79-80.

Labels applied in FIG. 6 illustrate at Rmin, the minimum radius developed upon rotation of my drill-bit 21, namely, the pilot bore radius; this minimum radius of cut is accomplished by the cutting elements on the arms 33- 34-35 on the upward pass of the drill-bit into the mass of solid matter to be bored. The maximum cutting radius is accomplished on the withdrawal path of the same drillbit and Without need for having previously withdrawn the tool for any adjustment. This maximum radius is designated Rmx, in FIG. 6. Naturally any intermediate cutting radius larger than Rmm, and less than Rmx. may also be cut with the tool indicated, as determined by appropriate selection of the relatively telescoped positioning of the inner and outer tubular members 48-31.

In order to actuate the parts for a given setting of the auxiliary cutting arms 65-7475, that is, for a given desired relatively telescoped relation between the inner and outer tubular members 48-31, I employ existing gear associated with a Kelly drive mechanism. Such gear inoludes near the upper end of the Kelly tube a shaft or stem S2 at the end of a lead-screw mechanism 83 (FIG. 5 The lead screw 83 engages a lead nut, not shown, but contained within suitably housed mechanism generally designated 84 and carried on a platform or bulkhead 85 xed near the upper end of the Kelly tube 19. The lead nut within the mechanism 84 is shown to be sprocketdriven at 86 `from a location considerably below that depicted in the main part of FIG. 5, but generally designated A at the lower sprocket drive shaft S7 (see the left-hand fragment of FIG. 5). At location A, the shaft 87 is journalled in the Kelly tube and is provided with an externally accessible squared or otherwise suitably congurated end 83, for removable attachment of a wrench or other hand or power-operated drive means for driving the shaft 87 and thus rotating the lead screw 83. Upon operation of the lead screw, against the reaction of the described splined engagements, the stem 82 will be elevated with respect to the position .shown in FIG. 5, thus propelling the head 31 by reason of attachment of .the enlarged end 89 of stem 82 at 90 to the closed end of the head 31. Such elevation of the stem 82 will lift the brackets 72 and thus by way of links 70 will retract the arms 65-74-75. Reversed rotation at shaft 87 will restore the previous position of arms 65-74-75, as will be understood.

In order that the drill of ymy .invention may be operated from still .another access location of the Kelly shaft .19, I show at location B (see the bottom left fragment of FIG. 5 another wrench or tool-access shaft 92, having bevel-gear engagement at 93 with a vertical shaft 94 communicating with location A by means of similar bevelgear means 95 associated with shaft S7.

The operation of my improved drill-bit will be more readily understood from an overall description in conjunction with the `diagrams of FIGS. `l to 4. Let it be .assume-d that the coking tower has accumulated a lcharge of coke and must be cleaned. First of all the port or door |14 at the bottom is dislodged, thus exposing the central region coaxial with the axis of the tower .and with the axis of the drill-bit. Preferably the closure `door has a flared or conical `configuration as suggested in FIG. 2, and Ithis configuration conforms generally to the canting of the pilot-cutting arms 3.3-34-35 of the drill head; such shaping (at 14') assures initial central location of the drill-bit as it engages the material to be dislodged. -I=t will be assumed that the drill-bit has been assembled after being suitably manipulated by way of the supporting hole or opening 42 (FG. 5), that it has been secu-red t-o the top of the Kelly shaft, and that the parts are in the relation sh-own in FIG. 2, in readiness to commence a pilot-boring operation.

The drive motor 23 on the car 22 is started in order to -put the Kelly shaft and drill bit in rotation, and at the same time fluid pressure is introduced at 24 to upwardly propel the shaft and drill bit. The auxiliary cutting arms y65474-375 will, of course, have been in retracted position by reason of the fact tha-t they were Iretracted at the end of the withdrawal cycle, following the last use thereof. The pilot cutting elements 33-34-35 safely clear the limits of the opening at the bott-om of the tower and begin their cutting work, starting with the alignedV shape 1li. Cutting proceeds to develop a pilot bore, indicated at 96 in FIG. 3, and pilot cutting continues until the drill passes int-o clear space beyond the upper limit 97 of the coke accumulation. As pilot-boring progressed, all dislodged fragments will be understood to have fallen freely to the conveyor belt 2d, for loading int-o transportation means 39 (FG. l).

FIG. 3 will be understood to suggest the upper limit of travel lof the Kelly tube 19 in which the piston 20 is near 'the upper limit of the cylinder or casing 16, and in which the drill head has cleared the upper limit 97 Iof the accumulated coke. position `location B will be exposed for manual access, and a tool 98 .is shown in FIG. 3 applied at location B to operate the lead screw mechanism 33t-841, for purposes of retracting the head 31 down on Ithe Ainner tubular member 4S, s-o that the auxiliary cutting arms 657'4-75 may be outwardly positioned as shown in FIG. 5, FIG. 6 and FIG. 9. Once so positioned, the tool 98 may be removed and rotation resumed for the Kelly shaft 19. At the same time, water under pressure may be withdrawn via port 24 so that the Kelly shaft 19 may be lowered as it rotates. The progress of the auxiliary or expanded-bore cut then commences.

Progress of the expanded-bore cut is illustrated in FIG. 1 for the case of tower 10, wherein the dare 99 of the cut colte is s-hown to be developed by arms 65-74-75 as the cut proceeds. Stability of this auxiliary cut is enhanced by drill-bit piloting at shoes A(WLMi-62' on the pilot bore 91S. Again, loose and dislodged clinlrers and particles fall naturally down the flare of the cut 99 and into the central passage 96 of the pilot bore, for removal by conveyor means 26. The auxiliary or second-stage cut continues until the entire vessel has been scoured free of clinlrers, and the arms 65-74-75 engage the bottom flared funnel shape of the tower 10;l preferably, the extended position of auxiliary cutting arms -65-74-75 establishes a conical auxiliary cut which essentially matches the liare of the tower surrounding the bottom opening thereof. At this point, rotation of the Kelly shaft 19 and hydraulic ow at 243 are stopped, and the parts will have the relation shown in FIG. 4. At this time also it will be noted that the upper tool-access location A will be exposed for insertion of the tool 918, so that the auxiliary cutting arm `65-7i'f-'7'i5 may be retracted by reason of `lead-screw operation at S3-S4i.

Once the auxiliary cut-ting arms have been retracted, the way is clear for hydraulic operation of t-he piston 20 to lower the drill-bit and Kelly shaft clear of the tower or vessel 10 and, in fact, to rest the drill-bit on the car 22. Removal of plugs Sil-Sti (FIGS. S-Sa) provides At this instant, the lower access tool Y access to the pin 49 by means of which the drill-bit may i derstood. Once the closure door 14 has been replaced on the cleaned tower 1%, said tower may be reinserted in the normal processing operation of the plant, and coke accumulation may be recycled.

It will be understood that l have described a basically simple and vastly Amore efficient means for accomplishing the effective cleaning of coking towers, sponge-iron reactor vessels, and the like and that in the employment of my invention down-time is reduced to an absolute minimum. The drill-bit of my invention utilizes for the most part existing drilling mechanisms and is readily adaptable to existing coiring towers and simil-ar reactor vessels.

While I have described the invention in detail in connection with the preferred form illustrated, it will be understood that modifications may be made within the scope of the invention as defined in the claims which follow.

I claim:

1. Apparatus for removing solid material deposits from a receptacle, said deposits having opposed terminal ends, including'a twoastage drill-bit operative to remove the solid material by two cutting operations each in a direction opposite to the other, comprising two slidably telescoping members adapted for unitary rota-tion and keyed against relative rotation, axially movable support means connected to said members for rotating the same, means carried by said support means and connected to one of said members operative to impart relative telescoping movement between said members', pilot-drill cutting means carried by the outer of said members at one axial end thereof, said pilot-drill cutting means being effective upon rotation of said bit about the axis of said mem-bers to cut a pilot-bore of a iirst limited diameter in said solid material, said pilot-cutting means initially penetrating said solid material from one end thereof to form said pilot bore and being shaped to generate a first substantially conical cut surface in said solid material with a dare in the direction of pilot-bore progression, a portion of the inner of said telescoping members projecting axially beyond the outer member Iat the end opposite said pilot-drill cutting means, auxiliary cutting means carried by said projecting portion of the inner telescoping member, bothV said pilot-drill cutting means and said auxiliary cutting means on completion of the cutting operation of the former projecting outwardly ybeyond the other end of the pilot bore, said auxiliary cutting means being selcctably movable between a first or retracted position and a second or auxiliary-cutting position, said auxiliary cutting means in said first position being fully contained within the pilot-bore diameter generated by said pilot-drill cutting means, said auxiliary cutting means in said second position when projected outwardly beyond said other end of the solid material being radially extended to cut on rotative and a reverse axial movement an enlarged auxiliary bore in the solid material greater than the pilot-bore diameter, said auxiliary cutting means in extended position being shaped to generate a second substantially conical cut surface with a are in the direction opposite to that of pilot-bore progression, and actuating means linking said auxiliary cutting Ameans to t-he outer of said telescoping members operative on relative axial telescoping movement between said tubular members to move said auxiliary cutting means from its first to its second position. Y

2. A two-stage drill-bit according to claim 1, in which said pilot-drill cutting means includes plural radially extending cutting arms about the drill-bit axis, said arms having axially outwardly facing cutting edges uniformly canted Ito contribute for generation of essentially said `first conical cut when rotated about the drill-bit axis, and in which said auxiliary cutting means when in said second position includes plural radially extending auxiliary cutt'i-n-g arms about the drill-bit axis, said auxiliary cutting arms having axially facing cutting edges uniformly canted assente 9 to contribute to generation of essen'tially said second conical cut when rotated about the drill-bit axis.

3. A two-stage drill-bit according to claim 2, in which the `arms of said pilot-drill cutting means are equally angularly spaced.

4. A `two-stage drill-bit according to claim 2, in which the arms of said auxiliary cutting means are equally ang-ularly spaced.

5. A two-stage drill-bit according to claim 2, in which each of the cutting edges of said pilot-drill cutting means includes along the length thereof a plurality of spaced cutting teeth, the teeth of one cutting edge being at different eifective cutting radii than those of another cutting edge.

6. A two-stage drill-bit according to claim 2, in which each of the cutting edges of said auxiliary cutting means includes along the length thereof a plurality of spaced cutting teeth, the teeth of one cutting edge being at different effective cutting radii than those of another cutting edge.

7. A two-stage drill-bit for cutting through a body of 4solid material having opposed terminal ends and having a bead end `for cutting in a forward axial direction and a tail end for connection to a source of rotary driving power, comprising two telescoping tubular members adapted for uni-tary rotation, plural pilot-drill radial cutting arms cairrie at the head end or said bit and at the forward end of one of the members, said arms having pilot-bore cutting edges Vun-iformly rearwardly canted to `generate essentially a iirst single conical cut at one terminal end of the solid material upon rotation about the drill-b-it axis, plural auxiliary-drill radial cutting arms, retractably carnied by the other of said members at its rear end, actuating means connecting said auxiliary-drill cutting arms to said one member operative on relative axial telescoping movement between said members to move said auxiliary-drill cutting arms from its retracted to an extended position, said lauxiliary-cutting arms being movable from a rst retracted position within the pilot-drill diameter during the cutting of the pilot-bore to a lsecond radially extended position when projected beyond the end of the pilot-boreat the opposite terminal end of the solid material, said auxiliary cutting arms :ha-ving expanded bore cutting edges which in extended position are uniformly canted in the direction opposite to that of said pilot-bore cutting edges to generate essentially a second single conical cut in the solid material upon drill-bit rotation, said second conical cut being in axially opposed direction to said first conical cut and being effective over a radial range beyond the confines of the pilot-bore diameter, whereby upon drill-bit rotation and movement in a forward axial direction and with said auxiliary-drill arms retracted said pilot cutting arms will make a pilot-bore on an entering cut at one terminal end of the solid material to be bored, the pilotbore extending completely through the solid material, and further whereby on completion of the pilot-bore cut and with said auxiliary-drill cutting arms projected beyond the end of the pilot-bore at the other terminal end of the solid material and extended, said auxiliary-drill cutting arms will enlarge lthe same pilot-bore to extended diameter on a withdrawing cut in said solid material.

8. A two-stage drill-bit for cutting through a body of solid material having opposed terminal ends comprising head means, pilot-cutting means at the axially forward end thereof, means connecting said head means to a source of rotary driving power for rotation about the drill-bit axis and for imparting axial movement to said head means in a forward and reverse direction, auxiliary cutting means carried by said head means at a location rearwardly of said pilot-cutting means and movable axially relative to said pilot-cutting means, actuating means connected to said head means and said auxiliary cutting means operative on axial relative movement between said auxiliary cutting means and said pilot-cutting means for selectively acutating said auxiliary cutting means between a retracted and an extended position, said auxiliary cutting means being retracted and contained within a pilot-bore cut by the pilot-cutting means in a forward direction from one terminal end to the other terminal end of said body of solid material and both cutting means being projected outwardly of said .pilot bore on completion of the cutting thereof, said auxiliary cutting means when in said projected outwardly position being extended on operation of said actuating means to -project generally radially outwardly of said head means and beyond the contines of the pilot bore diameter whereby on rotation thereof and axial movement in a reverse direction said auxiliary cutting means will cut a bore of a diameter larger than that of the pilot bore diameter and of the same length as said pilot bore, and stabilizing means carried by said head means in the zone of each said cutting means for guiding engagement by the pilot bore.

9. A two-stage drill-bit according to claim 8, in which said auxiliary cutting means comprises plural angularly spaced arms linked to :said `head means for actuation in unison between said positions.

10. A two-stage drill-bit according to claim 8, wherein said auxiliary cutting Imeans when extended includes outting elements facing in the opposite axial direction from said pilot-cutting mean-s, and each said stabilizing means comprises a plurality of circumferentia-lly spaced shoe means positioned effectively at the radial extent of the pilot bore on each said cutting means whereby both pilot and auxiliary cuts may be stabilized with respect to the same axis.

11. A two-stage drill-bit, comprising two slidably telescoping members adapted for unitary rotation and keyed against relative rotation, pilot-drill cutting means carried by the outer of said members of one axial end thereof, said cutting means being effective upon rotation of said bit about the axis of said members to cut a pilot bore of a first limited diameter, a portion of the inner of said telescoping members projecting axially beyond the outer member at the end opposite said pilot-drill cutting means, auxiliary cutting means carried by said projecting portion of the inner telescoping member, said auxiliary cutting means being selectably movable between a first or retracted position and a second or auxiliary-cutting position, `said auxiliary cutting means in said first position being fully contained within the pilot-bore diameter generated by said pilot-drill cutting means, said auxiliary cutting means in said `second position being radially extended to cut an enlarged auxiliary lbore greater than the pilotJbore diameter, and actuating means linking said auxiliary cutting means to the outer of said telescoping members, whereby said auxiliary cutting means may be moved from one to the other of its positions upon axial telescoping movement of said members, and generally tubular axially flexible seal means having one axial end sealingly connected to said outer telescoping member and its other axial end connected to said inner telescoping member, the axial fiexibility of said seal means being of such extent that said telescoping members may be moved to and from said iirst land second position-s while maintaining a sealed connection around the intert of said telescoping mem-bers.

12. A two-tage drill-bit, comprising head means including pilot-cutting means at the axially forward end thereof, means for connecting said head means to a source of rotary driving power for rotation about the drill-bit axis, said pilot-cutting means being of such effective radial extent about the drill-bit axis as t-o generate a pilot bore in a forward direction upon drill-bit rotation, auxiliary cutting means retractably carried -by said head means at a location rearwardly of said pilot-cutting means, said auxiliary cutting means when retracted being contained within the bore diameter generated by said pilotcutting means, said auxiliary cutting means when extended projection generally radially outwardly of said head means and beyond the contines of the pilct-bore diameter, said auxiliary cutting means when extended including cutting elements facing in the opposite axial direction from said pilot-cutting means, and actuating means operative within said head means for selectively actuating said auxiliary cutting means between its extended and retracted positions, said head means including stabilizing-shoe means positioned effectively at the radial extent of the pilot-bore, said shoe means being located rearwardly of both said pilot-cutting means and said auxiliary cutting means, whereby both pilot and auxiliary cuts may be stabilized with respect to the same axis.

13. A two-stage drill-bit according to claim 12, in which said shoe means comprises plural angularly spaced cylindrically arcuate elements at effectively pilot-bore radius.

14. A two-stage drill-bit according to claim 13 in which said head means includes at an axial location intermediate said pilot-cutting means and said auxiliary cutting means further stabilizing-shoe means effectively at the radial extent of said pilot-bore, whereby for a pilot-boring cut said head means may be stabilize-d at the axially spaced locations.

15. A two-stage drill-bit, comprising head means including pilot-cutting means at the axially forward end thereof, means for connecting said head means to a source of rotary driving power for rotation about the drill-bit axis, said pilot-cutting means being of such effective radial extent about the drill-bit axis as to generate a pilot-bore in a forward direction upon `drill-bit rotation, auxiliary cutting means retract-ably carried by said head means at a location rearwardly of said pilot-cutting means, said auxiliary cutting means when retracted being continued within the bore diameter generated by said pilotcutting means, said auxiliary cutting means when extended projecting generally radially outwardly of said head means and beyond the contines of the pilot-bore diameter, actuating means operative within said head means for selectively actuating said auxiliary cutting means between its extended and retracted positions, said actuating means comprising an elongated reciprocable member in axially slidable guided relati-on with said head means, said auxiliary cutting means including a cuttingV arm pivotally connected to said reciprocable member, a link connecting said head means to said cutting .arm at a location otset from said pilot connection, and stabilizing means carried by said head means rearwardly of said auxiliary cutting means and guided by .the pilot bore.

16. A two-stage drill-bit, comprising head means including pilot-cutting means at the axially forward end thereof, means for connecting said head means to a source of rotary driving power for rotation about the drill-bit axis, said pilot-cutting means being of such effective radial extent about the drill-bit axis as to generate a pilot-bore in a forward direction upon drill-bit rotation, auxiliary cutting means retractably carried by said head means at a location rearwardly of said pilot-cutting means, said auxiliary cutting means when retracted being contained within the bore diameter generated lby said pilot-cutting means, said auxiliary cutting means when extended projecting generally radially outwardly of said head means and beyond the contines of the pilot-bore diameter, actuating means operative within said head means for selectively actuating said auxiliary cutting means between its extended and retracted positions, said actuating means comprising an elongated reciprocable member in axially slidable guided relation with said head means, an .auxiliary-arm yoke carried on said reciprocable member at `a location rearward of said head means, said yoke including plural brackets at angularly spaced locations .and within the effective pilot-bore diameter, said auxiliary cutting means comprising cutting arms pivotally connected respectively to said brackets,

link means connecting said cutting arms to said head means at locations oiset from the pivot points thereof and stabilizing-shoe means carried by said head means rearwardly of said auxiliary cuttingmeans and guided by the pilot b-ore.

17. A two-stage drill-bit, comprising head means including pilot-cutting means at the axially forward end thereof, means for connecting said head means to a source of rotary driving power for rotation about the drill-bit axis, said pilot-cutting means being of such effective radial extent about the drill-bit axis as to generate a pilot-bore in a forward direction upon drill-bit rotation, auxiliary cutting means retractably carried by said head means at a location rearwardly of said pilot-cutting means, said auxiliary cutting means when retracted being contained within the bore diameter generated by said pilot-cutting means, said auxiliary cutting means when extended projecting generally radially outwardly of said head means and beyond the contines of the pilot-bore diameter, and actuating means operative within said head means for selectively actuating said auxiliary cutting means between its extended and retracted positions, said actuating means comprising an elongated reciprocable member in axially slidable guided relation with said head means, an auxiliaryarm yoke carried on said reciprocable member at a location rearward of said head means, said yoke including plural `brackets at angularly spaced locations and within the effective pilot-bore diameter, said auxiliary cutting means comprising cutting arms pivotally connected'respectively Ato said brackets, and link means connecting said cutting arms to said lhead means at locations offset from the pivot points thereof, and a stabilizing shoe of effectively pilot-bore radius and carried at the radial outer limit of-each of said brackets.

18. A two-stage drill-bit, comprising head means including pilot-cutting Vmeans at the-axially forward end thereof, means for connecting said head means to a source of rotary driving power for rotation about the drill-bit axis, said pilot-cutting means being of such effective radial extent about the drill-bit axis as to generate a pilot-bore in a forward direction upon drill-bit rotation, said pilot-cutting means comprising plural radially extending cutting arms forming fixed parts oflsaid head means at angularly spaced locations, auxiliary cutting means retractably carried by said head means at a location rearwardly of said pilotcutting means, said auxiliary cutting lmeans when retracted being contained within the bore diameter generated by said pilot-cutting means, said auxiliary cut-ting means when extended projecting generally radially outwardly of said head means and beyond the confines of the pilotbore diameter, and actuating means operative within said head means for selectively actuating said auxiliary cutting means between its extended and retracted positions, said actuating means comprising an elongated reciprocable member in axially slidable guided relation with said head means, an auxiliary-arm yoke carried on said reciproca-ble member at a location rearward of said head means, said yoke including plural brackets at angularly spaced localtions and within lthe effectiveV pilot-bore diameter, said auxiliary cutting means comprising cutting arms pivotally connected respectively to said brackets, and link means connecting said cutting arms to said head means at locations oiset from the pivot points thereof, said pilot-cutting arms and said auxiliary cutting arms being equal in number, with the arms of each plurality being in angularly interlaced relation, whereby in retracted position said auxiiiary cutting arms may be angularly intermediate said pilot-cutting arms.

19. A two-stage drill-bit according to claim 18, in which said yoke has at the root of each bracket a socket recess `adapted to receive `and locate the root end of the corresponding auxiliary cutting arm when in extended posi-tion.

References Cited by the Examiner UNITED STATES PATENTS Elliott 175-173 X Hogue 175-391 X McCloskey et al. 175-285 Alford 175-269 Huit 15-104.1

Santiage 175-268 Kuhn 15-10411 Hawthorne et al 175-391 York 175-408 ROBERT W. MICHELL, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CRRECTION Patent No. 3,280,416 october 25, 1966 James M. Forsyth It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 9, lines 26 and Z7, for "Carrie read carried same line 27, for "or" read of column 9, line 40, for "extended" read extending column l0, line 63, for "two-tage" read two-stage Signed and sealed this 5th day of September 1967.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Y Commissioner of Patents Attesting Officer 

7. A TWO-STAGE DRILL-BIT FOR CUTTING THROUGH A BODY OF SOILD MATERIAL HAVING OPPOSED TERMINAL ENDS AND HAVING A HEAD END FOR CUTTING IN A FORWARD AXIAL DIRECTION AND A TAIL END FOR CONNECTION TO A SOURCE OF ROTARY DRIVING POWER, COMPRISING TWO TELESCOPING TUBULAR MEMBERS ADAPTED FOR UNITARY ROTATION, PLURAL PILOT-DRILL RADIAL CUTTING ARMS CARRIE AT THE HEAD END OR SAID BIT AND AT THE FORWARD END OF ONE OF THE MEMBERS, SAID ARMS HAVING PILOT-BORE CUTTING EDGES UNIFORMLY REARWARDLY CANTED TO GENERATE ESSENTIALLY A FIRST SINGLE CONICAL CUT AT ONE TERMINAL END OF THE SOLID MATERIAL UPON ROTATION ABOUT THE DRILL-BIT AXIS, PLURAL AUXIALLY-DRILL RADIAL CUTTING ARMS, RETRACTABLY CARRIED BY THE OTHER OF SAID MEMBERS AT ITS REAR END, ACTUATING MEANS CONNECTING SAID AUXILIARY-DRILL CUTTING ARMS TO SAID ONE MEMBER OPERATIVE ON RELATIVE AXIAL TELESCOPING MOVEMENT BETWEEN SAID MEMBERS TO MOVE SAID AUXILIARY-DRILL CUTTING ARMS FROM ITS RETRACTED TO AN EXTENDED POSITION, SAID AUXILIARY-CUTTING ARMS BEING MOVABLE FROM A FIRST RETRACTED POSITION WITHIN THE PILOT-DRILL DIAMETER DURING THE CUTTING OF THE PILOT-BORE TO A SECOND RADIALLY EXTENDED POSITION WHEN PROJECTED BEYOND THE END OF THE PILOT-BORE AT THE OPPOSITE TERMINAL END OF THE SOLID MATERIAL, SAID AUXILIARY CUTTING ARMS HAVING EXPANDED BORE CUTTING EDGES WHICH IN EXTENDED POSITION ARE UNIFORMLY CANTED IN THE DIRECTION OPPOSITE TO THAT OF SAID PILOT-BORE CUTTING EDGES TO GENERATE ESSENTIALLY A SECOND SINGLE CONICAL CUT IN THE SOLID 